Method and apparatus for displaying characters on a screen

ABSTRACT

A method and apparatus for displaying characters on a TV screen in an electronic appliance such as a DVD player is disclosed. Vertically compressed character fonts are stored. When it is requested to display a character, the stored character font is read and displayed in a video field and then the character font is displayed again in the next video field, whereby flickering can be effectively eliminated with a reduced-size memory for storing fonts data.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method and apparatus for displaying characters on a screen and, more particularly, but not by way of limitation, to a method and apparatus for outputting OSD (on-screen display) characters on a TV screen in an electronic appliance such as a DVD player.

2. Description of the Related Art

Digital electronic appliances such as DVD players need fonts data to provide OSD (on-screen display) menus or additional services such as an electronic dictionary. The fonts data are commonly stored in a non-volatile memory included in the electronic appliances.

When it is requested to display some characters on a TV screen, the font data corresponding to the characters are read from the non-volatile memory and converted into video signals, whereby the characters are displayed on the screen.

A user may execute a desired function by selecting an item from the displayed OSD menu screen or requests a dictionary meaning of a word by selecting a character string displayed on the OSD screen.

To implement a function of an electronic dictionary as well as a simple OSD menu in an electronic appliance, fonts data for the characters to be displayed should be prepared. Fonts data are usually stored in a non-volatile memory device of a large size, which increases the manufacturing cost.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method and apparatus for displaying characters on a screen with reduced-sized fonts data wherein character fonts are compressed to be stored in a relatively small-sized non-volatile memory.

A method for displaying a character in accordance with the present invention is characterized in that it comprises the steps of: reading a character font from a storage means; displaying the read character font in a video field; and displaying the read character font in the next video field once again.

Another method for displaying a character in accordance with the present invention is characterized in that it comprises the steps of: reading a character font from a storage means; displaying a bit line of the read character font in a scan line; and displaying the bit line of the read character font in the next scan line once again.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention, illustrate the preferred embodiments of the invention, and together with the description, serve to explain the principles of the present invention.

In the drawings:

FIG. 1 depicts a block diagram of a DVD player embodying the present invention;

FIG. 2 a illustrates an exemplary character font in accordance with the invention;

FIG. 2 b shows a flow diagram for displaying a character in accordance with the invention; and

FIG. 3 illustrates a character to be displayed on a screen in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In order that the invention may be fully understood, preferred embodiments thereof will now be described with reference to the accompanying drawings.

The method for displaying characters on a screen in accordance with the invention may be applicable to multi-functional digital electronic appliances such as a DVD player.

FIG. 1 depicts a block diagram of a DVD player in which the present invention may be advantageously embodied. The DVD player comprises an optical pickup 11 for reading video and audio data recorded on an optical disk 10, an RF unit 12 for converting the RF signal received from the optical pickup 11 to binary signals, a digital signal processing unit 13 for retrieving original digital data from the binary signals, a video decoder 14 and audio decoder 15 for decoding the retrieved digital data to produce video and audio signals, a non-volatile memory 17 for storing fonts data for characters, an OSD generation unit 16 for generating OSD using the fonts data, a video mixer 19 for mixing the video signals generated by the video decoder 14 and the OSD generated by the OSD generation unit 16, and a control unit 18 for controlling the operation of each component.

The optical pickup 11 produces RF signals by reading signals recorded on the optical disk 10. The RF unit 12 produces binary signals after amplifying and shaping the RF signals.

The digital signal processing unit 13 processes the binary signals received from the RF unit 12 to retrieve original digital data. The video decoder 14 decodes the compressed video data of the retrieved digital data to output video signals. Likewise, the audio decoder 15 decodes the compressed audio data of the retrieved digital data to output audio signals. A TV, which is connected to the DVD player and receives the video and audio signals, reproduces video and audio signals through the screen and speakers.

The non-volatile memory 17 stores the fonts data for characters to be displayed. The fonts data represent a horizontal line of a character using a single line. As shown in FIG. 2 a, conventional fonts data represent a horizontal line of a character using two lines with a view to preventing flicker effects. Compared to the conventional fonts, therefore, the fonts in accordance with the invention become half in size and can be stored in a non-volatile memory of a half size.

In case of Korean character fonts, the space of the non-volatile memory 17 can be saved more if composition-type Korean fonts are employed instead of completion-type Korean fonts.

When characters inputted by a user is to be displayed on the screen, the control unit 18 reads the fonts stored in the non-volatile memory 17 and converts the fonts into video signals through the OSD generation unit 16, thereby displaying the characters on the screen.

In an interlaced scan, a horizontal line of a character should be displayed in both even and odd fields to prevent flicker effects. With the fonts stored in the non-volatile memory 17, which represent a horizontal line of a character using a single bit line, flicker effects can be avoided with the method to be explained below.

FIG. 2 b shows a flow diagram of the method for displaying characters in accordance with the invention.

The control unit 18 receives a user's key input and examines whether a request that requires the display of characters such as OSD display or electronic dictionary is received (S10).

For example, suppose that a request for displaying OSD is received (S11). Then the control unit 18 reads requested fonts stored in the non-volatile memory 17 and converts the fonts into video signals through the OSD generation unit 16, thereby displaying the characters on the screen.

To explain the process in more detail, the OSD generation unit 16 reads necessary fonts data (S12) and outputs each video line in synchronization with horizontal sync signals (S13). And then the OSD generation unit 16 repeats the process once again after a vertical sync signal occurs (S14). As a result, the data for a character is displayed in two adjacent scan lines of both even and odd fields within one frame, and thereby flickering does not happen.

The OSD for the characters generated by the OSD generation unit 16 is mixed with the picture video signal generated by the video decoder 14 by the video mixer 19 and applied to a connected TV.

FIG. 3 shows an example of displaying a Korean character ‘

’ by the above method.

The horizontal line of ‘

’ is displayed in the nth line (301) of an odd field and displayed again in the (n+1)th line (302) of an even field. Though the font data for the character has a single bit line corresponding to a horizontal line of the character, the horizontal line is displayed in both odd and even fields (303), whereby flickering is prevented.

In a non-interlaced display scheme, each bit line of font data is displayed repeatedly in two successive scan lines like 304 of FIG. 3, whereby the vertically compressed font is displayed normally on the screen.

After repeatedly displaying characters as many as required (S15), the control unit 18 stops the generation of OSD image by controlling the OSD generation unit 16 if a request for a function that does not need display of characters is received (S16).

The method for displaying characters on a screen in accordance with the invention saves memory space by reducing the memory space for needed storing fonts data.

While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of the invention. 

1. An apparatus for displaying characters, comprising: storage means for storing font data of a character; and character image generation means for displaying the font data of the character stored in said storage means by always repeating in successive even and odd fields a display of the font data.
 2. The apparatus set forth in claim 1, wherein the font data stored in said storage means represents a horizontal line of the character using a single bit line.
 3. The apparatus set forth in claim 1, wherein said character image generation means outputs the font data for the character in same scan lines in even and odd fields.
 4. An apparatus for displaying characters, comprising: storage means for storing font data of a character; and character image generation means for displaying each bit line of the font data of the character stored in said storage means always repeating in successive scan lines a display of the font data.
 5. The apparatus set forth in claim 4, wherein the font data of the character stored in said storage means represents a horizontal line of the character using a single bit line.
 6. The apparatus set forth in claim 5, wherein said character image generation means displays each bit line of the character twice.
 7. A method for displaying characters, comprising the steps of: reading font data of a character from storage means; displaying the read font data in a video field; and always displaying the read font data in the next video field again.
 8. The method set forth in claim 7, wherein the font data represents a horizontal line of the character using a single bit line.
 9. A method for displaying characters, comprising the steps of: reading font data of a character from storage means; displaying a bit line of the read font data in a scan line; and always displaying the bit line of the read font data in the next scan line again.
 10. The method set forth in claim 9, wherein the font data represents a horizontal line of the character using a single bit line.
 11. An apparatus for displaying characters for on-screen-display (OSD), comprising: a storage for storing font data of a character; and an OSD generation unit for reading the font data of the character, wherein the OSD generation unit always repeats a display of a line of the font data in successive lines of a display.
 12. The apparatus of claim 11, wherein the line of font data displayed is a horizontal line.
 13. The apparatus of claim 11, wherein a number of successive lines is two.
 14. The apparatus of claim 13, wherein the display is a progressive scan display.
 15. The apparatus of claim 13, wherein the display is an interlaced scan display.
 16. The apparatus of claim 15, wherein the line of the font data is displayed in a first line and a second line of the interlaced scan display, wherein the first and second lines are successive lines of the display and the first line is displayed in a first scan and the second line is displayed in a second scan. 